[bolger] Re: Convertible Cabin-top
The correct analogy is not between an open box and one with abutting flaps,
but between a box with closed and joined flaps (i.e. able to take both
compression and tension loads) and one with separated flaps, joined only at
one end (i.e. near the bow). The latter corresponds to the the "slotted
cabin" designs. The former is a box girder. In doing this experiment with
small boxes, the ability of closely fitting flaps to absorb compression loads
might give a misleading impression. If the flaps of the latter are trimmed
back so they don't can't make contact with each other and that box's rigidity
compared to that of a box with the flaps butted and taped together, I think
you might find some merit in my argument. I remain inclined to think that as
far as structural strength is concerned, the two halves of a "slotted" cabin
top have to be considered as independent, non-mutually supporting,
structures. As far as bouyancy generating structures above the sheer-line
("top-sides") go, can you suggest a suitable terminology that takes into
account the bouyancy of both the "top-sides" and the cabin sides, as so
dramatically described in Bolger's description of "Birdwatcher" laid on its
beams ends so the children can watch the fishies through the submerged cabin
windows?
Bill in tropical MN, wondering where I put my canoe's new license.
but between a box with closed and joined flaps (i.e. able to take both
compression and tension loads) and one with separated flaps, joined only at
one end (i.e. near the bow). The latter corresponds to the the "slotted
cabin" designs. The former is a box girder. In doing this experiment with
small boxes, the ability of closely fitting flaps to absorb compression loads
might give a misleading impression. If the flaps of the latter are trimmed
back so they don't can't make contact with each other and that box's rigidity
compared to that of a box with the flaps butted and taped together, I think
you might find some merit in my argument. I remain inclined to think that as
far as structural strength is concerned, the two halves of a "slotted" cabin
top have to be considered as independent, non-mutually supporting,
structures. As far as bouyancy generating structures above the sheer-line
("top-sides") go, can you suggest a suitable terminology that takes into
account the bouyancy of both the "top-sides" and the cabin sides, as so
dramatically described in Bolger's description of "Birdwatcher" laid on its
beams ends so the children can watch the fishies through the submerged cabin
windows?
Bill in tropical MN, wondering where I put my canoe's new license.
In a message dated 00-03-01 22:28:23 EST, you write:
<< - How about a telescoping cabin that would pop up? Normal looking
deck, then, after dropped sail, pull up the cabin. That way can keep a
low sail and have a tall cabin. >>
One of the major manufacturers of porta-potties already makes one. It is an
inflatable. Sort of a phone booth-like room with inflatable pillars on each
corner and a porta-pottie sitting on the floor of the booth.. An outrageous
price as I recall though.
<<How about a hinged cabin that rotates up? The hinge at the forward
edge of the cabin, triangular shaped sides to the cabin, and pops up
when sails are dropped>>
I thought of something similar...a set up like the sun screen on a
traditional baby buggy, ...side frames about 3-4 feet long, with pivot points
aft and the "top" of the frame made to fold down forward (side frames joined
forward at a central point ) or to fold "up" aft to extend over the storage
compartment of an Oldshoe (or similar small boat), which could have a
portapottie placed in it.
Regards, Warren
<< - How about a telescoping cabin that would pop up? Normal looking
deck, then, after dropped sail, pull up the cabin. That way can keep a
low sail and have a tall cabin. >>
One of the major manufacturers of porta-potties already makes one. It is an
inflatable. Sort of a phone booth-like room with inflatable pillars on each
corner and a porta-pottie sitting on the floor of the booth.. An outrageous
price as I recall though.
<<How about a hinged cabin that rotates up? The hinge at the forward
edge of the cabin, triangular shaped sides to the cabin, and pops up
when sails are dropped>>
I thought of something similar...a set up like the sun screen on a
traditional baby buggy, ...side frames about 3-4 feet long, with pivot points
aft and the "top" of the frame made to fold down forward (side frames joined
forward at a central point ) or to fold "up" aft to extend over the storage
compartment of an Oldshoe (or similar small boat), which could have a
portapottie placed in it.
Regards, Warren
1 - How about a telescoping cabin that would pop up? Normal looking
deck, then, after dropped sail, pull up the cabin. That way can keep a
low sail and have a tall cabin.
2 - How about a hinged cabin that rotates up? The hinge at the forward
edge of the cabin, triangular shaped sides to the cabin, and pops up
when sails are dropped.
I really like the idea! Low center of gravity while sailing, tall cabin
at anchor (home made anchor that is). Wonder why a boat like this
hasn't been designed yet?
deck, then, after dropped sail, pull up the cabin. That way can keep a
low sail and have a tall cabin.
2 - How about a hinged cabin that rotates up? The hinge at the forward
edge of the cabin, triangular shaped sides to the cabin, and pops up
when sails are dropped.
I really like the idea! Low center of gravity while sailing, tall cabin
at anchor (home made anchor that is). Wonder why a boat like this
hasn't been designed yet?
I have a vague recollection of something like this that was available
in the 1970's, possibly by Oday.
short-@...wrote:
original article:http://www.egroups.com/group/bolger/?start=3346
in the 1970's, possibly by Oday.
short-@...wrote:
original article:http://www.egroups.com/group/bolger/?start=3346
> 1 - How about a telescoping cabin that would pop up? snip
> 2 - How about a hinged cabin that rotates up? snip
>
> snip. Wonder why a boat like this
> hasn't been designed yet?
>
On Tue, 29 Feb 2000Wmrpage@...wrote:
gunwhales. They are *always* structurally significant, of course.
But the top of the boat (the "upper deck"?).
They are structurally significant, too.
Imagine a cardboard box, with no top at all.
Then imagine a cardboard box, with two flaps, that, when firmly
taped down, don't quite meet in the center.
Which is stiffer?
The one with the attached flaps, and by a long shot.
Chris Crandallcrandall@...(785) 864-4131
Department of Psychology University of Kansas Lawrence, KS 66045
I have data convincingly disconfirming the Duhem-Quine hypothesis.
> This is pure B.S., but I think:First, topsides means the side of the hull, from the waterline to the
> 1) Yes: the great freeboard of the "slot-top" cabins like
> "Birdwatcher", etc. are probably very important to their ultimate
> stability. (pure B.S., of course) I very much doubt that the topsides
> are structurally significant
gunwhales. They are *always* structurally significant, of course.
But the top of the boat (the "upper deck"?).
They are structurally significant, too.
Imagine a cardboard box, with no top at all.
Then imagine a cardboard box, with two flaps, that, when firmly
taped down, don't quite meet in the center.
Which is stiffer?
The one with the attached flaps, and by a long shot.
Chris Crandallcrandall@...(785) 864-4131
Department of Psychology University of Kansas Lawrence, KS 66045
I have data convincingly disconfirming the Duhem-Quine hypothesis.
> > 1. In the Bolger and Michalak designs, the slot-top cabin is used toThe wide "cabin top/side deck" of the Catfish is an important part of
> > keep the boat from swamping in the case of a knock-down and it may
> also
> > provide some structural value as well. If I start with a design like
> > Catfish and remove the permanent cabin, am I significantly
> compromising
> > the structure and safety (knock-down) of the design?
the design, and while I think some alteration is feasible, it does
require some thought.
Structurally, in order to keep the boat clear for sprawling and
sleeping, there is very little framing amidships. The deck contributes
a major part to the stiffness (torsion resistance) of the center part
of the boat. If you were to make the deck real narrow, I think you
might consider putting in a midships frame.
From the point of view of safety, the deck keeps the water out in a
knockdown, and making the deck narrower would detract from that
function.
If you were to try to re-think the boat into a more conventional
arrangement, you could put a full bulkhead across the boat a foot or so
aft of the mast to enclose a cuddy. The cabin top would be solid. The
deck aft of that point would be elimated. Along the sides of boat there
would be side-facing seats at a comportable height. The space beneath
the seats would be enclosed for flotation. You might need another frame
between the bulkhead and the aft end of the cockpit. With this
arrangement, you could sit well out to the side for optimum use of live
ballast with your back comfortable against the hull side. This is like
the Cynthia J. and worked out well.
Compared to the original, the boat would probably be heavier, better
for daysailing, not suitable for sleeping, faster in a breeze (due to
the better use of live ballast). And, there is the danger that you
would still have Chebacco-envy.
Peter
This is pure B.S., but I think:
1) Yes: the great freeboard of the "slot-top" cabins like "Birdwatcher", etc.
are probably very important to their ultimate stability. (pure B.S., of
course) I very much doubt that the topsides are structurally significant - if
the top was a continuous web or such like, it would form a side of a box
girder; with a slot down the middle - even if only a saw kirf, much less the
designed "slots", I think its structural value would approach zero.
2) Yes: You have identified windage and weight (Cg) as problems. Whether or
when these would be unaccepable to performance or safety, I don't have a clue.
(3) (unsolicited - but a matter that interests me) - Why not a"tent" as
shelter for converting a daysailer into a temporary accomodation? I suspect
that designing tension fabric structures that will withstand winds, while
giving crew access when the anchor starts dragging, etc. is a non-trivial
exercise. The market for such accomodations is presumalby miniscule.
However, I do remember my astonished admiration of the first "Timberline"
free standing tent (that I encountered) so many years ago. I have day-dreamed
about a simple sharpie that would use standard free-standing tents as
accomodations for use on Rainy Lake, or Lake of the Woods or such - but my
speculations always end up wondering what happens when you are (1) in a
sleeping bag, (2) inside a tent, (3) the anchor is dragging, and (4) all this
"*#@+*&^~" is between you and the essential "stuff" (i.e. anchor rode, motor,
halyards, etc.) I haven't got a clue, but I think a well thought out
"soft-top" would make more sense than a "convertible" "hard top". Not that I
have any intelligent suggestions to make about either.
Bill, in truly tropical MN, searching for the estate of Dobler.
1) Yes: the great freeboard of the "slot-top" cabins like "Birdwatcher", etc.
are probably very important to their ultimate stability. (pure B.S., of
course) I very much doubt that the topsides are structurally significant - if
the top was a continuous web or such like, it would form a side of a box
girder; with a slot down the middle - even if only a saw kirf, much less the
designed "slots", I think its structural value would approach zero.
2) Yes: You have identified windage and weight (Cg) as problems. Whether or
when these would be unaccepable to performance or safety, I don't have a clue.
(3) (unsolicited - but a matter that interests me) - Why not a"tent" as
shelter for converting a daysailer into a temporary accomodation? I suspect
that designing tension fabric structures that will withstand winds, while
giving crew access when the anchor starts dragging, etc. is a non-trivial
exercise. The market for such accomodations is presumalby miniscule.
However, I do remember my astonished admiration of the first "Timberline"
free standing tent (that I encountered) so many years ago. I have day-dreamed
about a simple sharpie that would use standard free-standing tents as
accomodations for use on Rainy Lake, or Lake of the Woods or such - but my
speculations always end up wondering what happens when you are (1) in a
sleeping bag, (2) inside a tent, (3) the anchor is dragging, and (4) all this
"*#@+*&^~" is between you and the essential "stuff" (i.e. anchor rode, motor,
halyards, etc.) I haven't got a clue, but I think a well thought out
"soft-top" would make more sense than a "convertible" "hard top". Not that I
have any intelligent suggestions to make about either.
Bill, in truly tropical MN, searching for the estate of Dobler.
Oops, URL for Storm Petrel article got cut off:
http://members.xoom.com/_XMCM/merrellc1/Files/petrel.pdf
http://members.xoom.com/_XMCM/merrellc1/Files/petrel.pdf
"stepehn f. heil" <casahei-@...> wrote:
original article:http://www.egroups.com/group/bolger/?start=3292
seems to be exactly what you are describing--an open boat (albeit with
wide, high side decks) with a removeable canvas cover over the forward
cockpit to make a sort of cuddy. See the study plans at
http://www.instantboats.com/catfish.htmif it's not clear from the
pics. With some sort of bench seating, and perhaps narrower side
decks, I think it would meet your needs.
If you are looking for more of a daysailer with a tiny cuddy, or at
least dry stowage for your gear and a porta-potti, how about Storm
Petrel? See the pics in the vault and the copy of Bolger's SMALL BOATS
chapter on Chuck Merrell's site athttp://members.xoom.com/_XMCM/merre
llc1/Files/petrel.pdf
top was very light, a canvas-and-battens affair, and perhaps add a
little ballast. The ultra-simple 20' Zephyr has always seemed to me to
be perfect for this kind of conversion, especially if built frameless
with a doubled or tripled, flanged gunwale Dave Carnell-style, and a
Michalak-style pivoting leeboard with some added lead ballast. See
http://www.instantboats.com/zephyr.htmif you haven't got INSTANT
BOATS. Hmmm, now you've got ME thinking....
Keep dreaming!
Matthew Long
original article:http://www.egroups.com/group/bolger/?start=3292
> Concerns:also
> 1. In the Bolger and Michalak designs, the slot-top cabin is used to
> keep the boat from swamping in the case of a knock-down and it may
> provide some structural value as well. If I start with a design likecompromising
> Catfish and remove the permanent cabin, am I significantly
> the structure and safety (knock-down) of the design?Not to be picky here, but Catfish does NOT have a cabin, in fact it
seems to be exactly what you are describing--an open boat (albeit with
wide, high side decks) with a removeable canvas cover over the forward
cockpit to make a sort of cuddy. See the study plans at
http://www.instantboats.com/catfish.htmif it's not clear from the
pics. With some sort of bench seating, and perhaps narrower side
decks, I think it would meet your needs.
If you are looking for more of a daysailer with a tiny cuddy, or at
least dry stowage for your gear and a porta-potti, how about Storm
Petrel? See the pics in the vault and the copy of Bolger's SMALL BOATS
chapter on Chuck Merrell's site athttp://members.xoom.com/_XMCM/merre
llc1/Files/petrel.pdf
> 2. If I start with a cabin-less design that is realatively light inIf I wanted a convertible, I would go this route and just make sure the
> weight, adding the convertible top may raise the center of gravity and
> windage of what was a good open boat design.
top was very light, a canvas-and-battens affair, and perhaps add a
little ballast. The ultra-simple 20' Zephyr has always seemed to me to
be perfect for this kind of conversion, especially if built frameless
with a doubled or tripled, flanged gunwale Dave Carnell-style, and a
Michalak-style pivoting leeboard with some added lead ballast. See
http://www.instantboats.com/zephyr.htmif you haven't got INSTANT
BOATS. Hmmm, now you've got ME thinking....
Keep dreaming!
Matthew Long
Hello
PCB has designed at least one like this. His "Centennial" design comentary refers to one and I think the boat is shown with it on.
While I havn't tried it with boat cabin tops I know from previous experiece with "detachable bits" that its largely a matter of personal style as to wether they work out. I love designing and making attachments but seldon can be bothered making use of them. Some examples - the loft in my garage, the nesting dinghy (it never gets broken down) etc.
Regards - Foster
Stepehn wrote:
Is anyone interested in engaging in a discussion of the pros, cons and
possible construction of a removable cabin-top. The concept would be
that of an open cockpit sailboat that could be converted to a
camp-cruiser with the addition of a removable hardtop.
PCB has designed at least one like this. His "Centennial" design comentary refers to one and I think the boat is shown with it on.
While I havn't tried it with boat cabin tops I know from previous experiece with "detachable bits" that its largely a matter of personal style as to wether they work out. I love designing and making attachments but seldon can be bothered making use of them. Some examples - the loft in my garage, the nesting dinghy (it never gets broken down) etc.
Regards - Foster
Stepehn wrote:
Is anyone interested in engaging in a discussion of the pros, cons and
possible construction of a removable cabin-top. The concept would be
that of an open cockpit sailboat that could be converted to a
camp-cruiser with the addition of a removable hardtop.
Is anyone interested in engaging in a discussion of the pros, cons and
possible construction of a removable cabin-top. The concept would be
that of an open cockpit sailboat that could be converted to a
camp-cruiser with the addition of a removable hardtop.
For a better idea of what I'm talking about, here are a few references
from "the Sharpie Book" by Reuel Parker which is the only place I've
seen this mentioned.
1st Reference - Page 78, Figure 5-8. Removable cuddy cabin
"The cuddy cabin can be made as an add-on --- almost like a convertible
hardtop. To do this, you can deck and fit out the sharpie as an open
boat, and make the cuddy to fit over the front- and side-deck coamings,
to which it is through-bolted. The back of the cuddy can be left open,
bulkheaded to fit snugly to either a bridge deck or thwart (which may
be in turn bulkheaded off from the cockpit to make the cabin
watertight), or a canvas-and-screen cover can be made to close the back
of the cuddy."
2nd Reference - Page 126, Figure 6-10 27-foot New Haven Sharpie
The 27-foot New Haven sharpie looks like a beautiful boat but is too
big for me. The study plans show a very attractive looking convertibel
cabin top. Where my imagination has taken me is to something like the
Catfisf beach-cruiser but without the slot-top cabin but rather a
removable cabin-top aboit 7 to 8 feet long. It may ne=ot even need to
be that long if some space is available for your toes under the
foredeck. The top could be made with the Birdwatcher slot allowing easy
access to the rig and bow in fair weather. For sleaping abd foul
weather accomodations the slot and after end of the cabin could be
enclose with canvas.
Concerns:
1. In the Bolger and Michalak designs, the slot-top cabin is used to
keep the boat from swamping in the case of a knock-down and it may also
provide some structural value as well. If I start with a design like
Catfish and remove the permanent cabin, am I significantly compromising
the structure and safety (knock-down) of the design?
2. If I start with a cabin-less design that is realatively light in
weight, adding the convertible top may raise the center of gravity and
windage of what was a good open boat design.
I'd love to hear comments and advice on my ramblings.
possible construction of a removable cabin-top. The concept would be
that of an open cockpit sailboat that could be converted to a
camp-cruiser with the addition of a removable hardtop.
For a better idea of what I'm talking about, here are a few references
from "the Sharpie Book" by Reuel Parker which is the only place I've
seen this mentioned.
1st Reference - Page 78, Figure 5-8. Removable cuddy cabin
"The cuddy cabin can be made as an add-on --- almost like a convertible
hardtop. To do this, you can deck and fit out the sharpie as an open
boat, and make the cuddy to fit over the front- and side-deck coamings,
to which it is through-bolted. The back of the cuddy can be left open,
bulkheaded to fit snugly to either a bridge deck or thwart (which may
be in turn bulkheaded off from the cockpit to make the cabin
watertight), or a canvas-and-screen cover can be made to close the back
of the cuddy."
2nd Reference - Page 126, Figure 6-10 27-foot New Haven Sharpie
The 27-foot New Haven sharpie looks like a beautiful boat but is too
big for me. The study plans show a very attractive looking convertibel
cabin top. Where my imagination has taken me is to something like the
Catfisf beach-cruiser but without the slot-top cabin but rather a
removable cabin-top aboit 7 to 8 feet long. It may ne=ot even need to
be that long if some space is available for your toes under the
foredeck. The top could be made with the Birdwatcher slot allowing easy
access to the rig and bow in fair weather. For sleaping abd foul
weather accomodations the slot and after end of the cabin could be
enclose with canvas.
Concerns:
1. In the Bolger and Michalak designs, the slot-top cabin is used to
keep the boat from swamping in the case of a knock-down and it may also
provide some structural value as well. If I start with a design like
Catfish and remove the permanent cabin, am I significantly compromising
the structure and safety (knock-down) of the design?
2. If I start with a cabin-less design that is realatively light in
weight, adding the convertible top may raise the center of gravity and
windage of what was a good open boat design.
I'd love to hear comments and advice on my ramblings.